ringgold

Got an L76 aluminum 6.0L block at the machine shop. Needs a slight bore to get it back in shape and because of this the stock pistons that were in it will be too small. Found some cheap factory replacement pistons that are .020" bigger. I have heard that these aluminum blocks are really strong, but the iron blocks are a little stronger. Will this .020" larger bore with a good hone weaken the cylinders enough to where I shouldn't pursue turboing it and pushing on it with forced induction?

I am trying to jump on the super cheap turbo LS bandwagon, but in the process learn about all of these different LS engine combinations and what not. I have no real experience working with one, but do a lot of reading online.

I was also told to source a set of 317 casting heads for this engine if I do want to go the turbo route, as they will lower the comp ration down a little bit and make it a little safer for turboing. The heads that came on this L76 that I have may be damaged beyond working with. I talked with TEA and sent them several pics of the heads that I pulled from my engine and they told me that I would probably sink too much money into them to get them back into shape to use. TEA is who suggested that I source a set of 317's if I were to go the turbo route. But, if this bore and hone actually weaken it too much and I run a risk of tearing it all up before I start leaning on it and trying to make some power I may scrap this whole engine and go with something different.

My plan was to freshen up the L76 that I got for $100. I was going to tear it down, get it checked out and try to reuse the stock pistons that were in it with a new set of rings that were opened up a bit. Maybe a new set of main and rod bearings, new oil pump, etc. Trying to put together a nice semi fresh engine for cheap, which at this point I think I can still do.

I made this same post over on another forum, but I am getting limited opinions.

Always2Slow

iTrader: (8)

An Iron block is much better for turboing and a .020 overbore should be okay. I don't think it will severely limit your boost, but be mindful about it when throwing more at it. The aluminum blocks are typically a .010 hone and done type deal.

ringgold

I don't have a manual for the L76 engine. I do have a full manual that I found online for the LQ4 and LQ9 engines.

I found a cheap set of stock style replacement pistons from Enginetech Pistons. They only come in the stock 4" bore and then go up to 4.020" so that is why I am saying a .020" overbore.

I wished I could find more info on this block and what the factory suggests as far as bore size. Are there links online to where I can look at factory repair manuals for this type engine?

Also, if the .020" overbore is too much material being removed from this aluminum block for a turbo setup, is it too much all together for this type block? Will I have problems if I put together a setup with good heads and cam?

ringgold

I am going to stop by the machine shop in a little while and see if they can sonic test it and see what the wall thickness is on that block. See what is safe.

A_VAS

iTrader: (16)

those pistons aren't suitable for boost...that is the limiting factor not your proposed block. You should be getting a forged piston set...and get whatever overbore size you need to clean up the block. Probably 4.010 will work fine

ringgold

Got the block at another machine shop that does a lot of work with the LS engines. Going to see what we can get away with as far as bore and the stock pistons that were removed from the engine.

FastKat

iTrader: (10)

Welcome to the LS world!

Rather than a manual, I used this book for reference. It was pretty good.


Your machine shop should be working on this for you. They'll measure your pistons, identify the alloy, and cut the hole based on that... especially if you're using aftermarket pistons.


I think it depends on what you want to do. .005" will be good if your machine shop can remove that little material and still get a good round hole. I did .030" but I am not running boost. I think either of those should be fine, but many will disagree and say stay away from .030" over, especially with boost. They might be right.

I think sonic testing only tests the iron and not the aluminum? I could be wrong. I wouldn't waste your time or money with that. If in doubt, just buy a smaller piston.

This is good info. If you have to buy oversized pistons, get ones that are made for boost. There are affordable ones out there. I've heard good things about RaceTec and AutoTec pistons.

ringgold

Well, here is what I did so far. I bought a set of .010" over Wiseco Junkyard series pistons. They are made to fit on a stock rod. I have Gen IV rods and from what I was told by a reputable shop they are a little beefier and they have bigger bolts as well.

The block has been bored and honed according to the pistons and a new set of cam bearings installed in it.

I could probably get away with reusing some of the stock bearings, but since it is all apart I would like to install new rod and main bearings. Plus some of the rod bearings, especially on rods 1-4 the bearings have some wear on them that I am unsure of. I have heard mixed things about people pulling bearings from LS engines. Some say their 200k mile engine had bearings that looked brand new and then others say theirs had some wear marks. So right now I am researching bearings and clearances.